zipoutputstreambuf.cpp

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/*
  Zipios -- a small C++ library that provides easy access to .zip files.
 
  Copyright (C) 2000-2007  Thomas Sondergaard
  Copyright (c) 2015-2022  Made to Order Software Corp.  All Rights Reserved
 
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.
 
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.
 
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#include "zipoutputstreambuf.hpp"
 
#include "zipios/zipiosexceptions.hpp"
 
#include "ziplocalentry.hpp"
#include "zipendofcentraldirectory.hpp"
 
 
namespace zipios
{
 
 
namespace
{
 
 
void writeZipCentralDirectory(
      std::ostream & os
    , FileEntry::vector_t & entries
    , std::string const & comment)
{
    ZipEndOfCentralDirectory eocd(comment);
    eocd.setOffset(os.tellp());  // start position
    eocd.setCount(entries.size());
 
    std::size_t central_directory_size(0);
    for(auto it = entries.begin(); it != entries.end(); ++it)
    {
        (*it)->write(os);
        central_directory_size += (*it)->getHeaderSize();
    }
 
    eocd.setCentralDirectorySize(central_directory_size);
    eocd.write(os);
}
 
 
} // no name namespace
 
 
ZipOutputStreambuf::ZipOutputStreambuf(std::streambuf * outbuf)
    : DeflateOutputStreambuf(outbuf)
{
}
 
 
ZipOutputStreambuf::~ZipOutputStreambuf()
{
    // avoid possible exceptions when writing the central directory
    try
    {
        finish();
    }
    catch(...)
    {
    }
}
 
 
void ZipOutputStreambuf::closeEntry()
{
    if(!m_open_entry)
    {
        return;
    }
 
    switch(m_compression_level)
    {
    case FileEntry::COMPRESSION_LEVEL_NONE:
        overflow(); // flush
        break;
 
    default:
        closeStream();
        break;
 
    }
 
    updateEntryHeaderInfo();
    setEntryClosedState();
}
 
 
void ZipOutputStreambuf::close()
{
    finish();
}
 
 
void ZipOutputStreambuf::finish()
{
    if(!m_open)
    {
        return;
    }
    m_open = false;
 
    std::ostream os(m_outbuf);
    closeEntry();
    writeZipCentralDirectory(os, m_entries, m_zip_comment);
}
 
 
void ZipOutputStreambuf::putNextEntry(FileEntry::pointer_t entry)
{
    closeEntry();
 
    // if the method is STORED force uncompressed data
    if(entry->getMethod() == StorageMethod::STORED)
    {
        // force to "no compression" when the method is STORED
        m_compression_level = FileEntry::COMPRESSION_LEVEL_NONE;
    }
    else
    {
        // get the user defined compression level
        m_compression_level = entry->getLevel();
    }
    m_overflown_bytes = 0;
    switch(m_compression_level)
    {
    case FileEntry::COMPRESSION_LEVEL_NONE:
        setp(&m_invec[0], &m_invec[0] + getBufferSize());
        break;
 
    default:
        init(m_compression_level);
        break;
 
    }
 
    m_entries.push_back(entry);
 
    std::ostream os(m_outbuf);
 
    // Update entry header info
    entry->setEntryOffset(os.tellp());
    static_cast<ZipLocalEntry *>(entry.get())->ZipLocalEntry::write(os);
 
    m_open_entry = true;
}
 
 
void ZipOutputStreambuf::setComment(std::string const & comment)
{
    m_zip_comment = comment;
}
 
 
//
// Protected and private methods
//
 
int ZipOutputStreambuf::overflow(int c)
{
    std::size_t const size(pptr() - pbase());
    m_overflown_bytes += size;
    switch(m_compression_level)
    {
    case FileEntry::COMPRESSION_LEVEL_NONE:
    {
        // Ok, we are STORED, so we handle it ourselves to avoid "side
        // effects" from zlib, which adds markers every now and then.
        m_crc32 = crc32(m_crc32, reinterpret_cast<Bytef const *>(&m_invec[0]), size); // update crc32
        size_t const bc(m_outbuf->sputn(&m_invec[0], size));
        if(size != bc)
        {
            // Without implementing our own stream in our test, this
            // cannot really be reached because it is all happening
            // inside the same loop in ZipFile::saveCollectionToArchive()
            throw IOException("ZipOutputStreambuf::overflow(): write to buffer failed."); // LCOV_EXCL_LINE
        }
        setp(&m_invec[0], &m_invec[0] + getBufferSize());
 
        if(c != EOF)
        {
            *pptr() = c;
            pbump(1);
        }
 
        return 0;
    }
 
    default:
        return DeflateOutputStreambuf::overflow(c);
 
    }
}
 
 
 
int ZipOutputStreambuf::sync() // LCOV_EXCL_LINE
{
    return DeflateOutputStreambuf::sync(); // LCOV_EXCL_LINE
}
 
 
 
void ZipOutputStreambuf::setEntryClosedState()
{
    m_open_entry = false;
    m_crc32 = crc32(0, nullptr, 0);
 
}
 
 
void ZipOutputStreambuf::updateEntryHeaderInfo()
{
    if(!m_open_entry)
    {
        return;
    }
 
    std::ostream os(m_outbuf);
    int const curr_pos(os.tellp());
 
    // update fields in m_entries.back()
    FileEntry::pointer_t entry(m_entries.back());
    entry->setSize(getSize());
    entry->setCrc(getCrc32());
    entry->setCompressedSize(curr_pos - entry->getEntryOffset() - static_cast<ZipLocalEntry *>(entry.get())->ZipLocalEntry::getHeaderSize());
 
    // write ZipLocalEntry header to header position
    os.seekp(entry->getEntryOffset());
    static_cast<ZipLocalEntry *>(entry.get())->ZipLocalEntry::write(os);
    os.seekp(curr_pos);
}
 
 
} // zipios namespace
 
// Local Variables:
// mode: cpp
// indent-tabs-mode: nil
// c-basic-offset: 4
// tab-width: 4
// End:
 
// vim: ts=4 sw=4 et